Control device for vehicle traveling

ABSTRACT

The autonomous LC control is started in response to receiving a start instruction of autonomous lane change. When the driver performs a steering intervention in a same direction as a direction of steering requested by the autonomous LC control, and establishment of a stop condition of lane change is not recognized, during execution of the autonomous LC control, the autonomous driving control is continued. When the steering intervention in the same direction is performed, and establishment of the stop condition is recognized, during execution of the autonomous LC control, termination of the autonomous driving control is announced.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application claims priority to Japanese Patent Application No.2016-237705 filed on Dec. 7, 2016, the entire contents of which areherein incorporated by reference.

BACKGROUND Field

Embodiments of the present disclosure relates to a control device forvehicle traveling, and particularly relates to a control device forvehicle traveling for achieving autonomous driving including autonomouslane change of a vehicle.

Background Art

Japanese Patent Laid-Open No. 2015-174494 discloses a lane changeassisting device for causing a vehicle to perform lane changeautonomously. The above described lane change assisting device firstlysets a target acceleration at the time of lane change. Next, the lanechange assisting device calculates a desired distance sustainable timebased on the target acceleration. The desired distance sustainable timeis a time period during which a sufficient relative distance can besustained between the vehicle and another vehicle. Next, the lane changeassisting device sets a target route for completing lane change within arange of the desired distance sustainable time. When the target routecan be set, the vehicle is caused to perform lane change autonomously.On the other hand, when it is determined that lance change within thedesired distance sustainable time is difficult, the arithmetic operationfor lane change is ended.

LIST OF RELATED ART

Following is a list of patent literatures which the applicant hasnoticed as related arts of the present disclosure.

[Patent Literature 1]

Japanese Patent Laid-Open No. 2015-174494

SUMMARY

While a vehicle is traveling by autonomous driving control, a steeringintervention by a driver may occur. In the vehicle equipped with theabove described conventional lane change assisting device, it isnecessary to assume an intervention by the driver. For example, when asteering intervention that assists lane change is performed by thedriver during the lane change is being autonomously performed by thelane change assisting device, it is appropriate to reflect such anassist in a vehicle behavior.

If the intervention by the driver coincides with the determination ofthe autonomous lane change, it is desirable not to cancel the mode ofautonomous driving. Meanwhile, when the driver forces to perform lanechange under a situation in which lane change should be waited accordingto the decisions of the autonomous lane change, it is unfavorable thatthe mode of autonomous driving is continued because the intention of thedriver does not coincide with the intention of the autonomous driving.

However, in the above described conventional lane change assistingdevice, the relationship between how the steering intervention is doneby the driver and when the autonomous driving should be maintained isnot defined. If it is defied that the mode of autonomous driving shouldbe cancelled whenever there is a steering intervention, frequentcancellation of the mode may cause the driver to be annoyed. On theother hand, according to the setting that the mode is never canceled atall times, the driver may tend to feel a sense of discomfort becauseautonomous driving that is not in line with the intention is continued.

Embodiments of the present disclosure have been made to solve the abovedescribed problem, and an object of an embodiment of the presentdisclosure is to provide a control device for vehicle traveling that canlet a driver know, when the driver forces to perform lane change under asituation in which lane change should not be performed, that the lanechange forcibly done by the driver does not coincide with an intentionof the decision of the autonomous driving, without giving much annoyanceto the driver.

To achieve the above mentioned purpose, a first aspect of an embodimentof the present disclosure is a control device for vehicle traveling thatexecutes autonomous driving control that causes a vehicle to travelautonomously,

-   the autonomous driving control including autonomous lane change    control that achieves autonomous lane change of a vehicle, and-   the control device for vehicle traveling executing:-   a process of starting the autonomous lane change control in response    to receiving an instruction to start the autonomous lane change;-   a process of determining whether or not a stop condition of the    autonomous lane change is established;-   a process of giving priority to steering of a driver over steering    that is caused by the autonomous lane change control when there is a    steering intervention by the driver during execution of the    autonomous lane change control;-   a process of continuing the autonomous driving control when a driver    performs a steering intervention in a same direction as a direction    of steering that is requested by the autonomous lane change control,    and establishment of the stop condition is not recognized, during    execution of the autonomous lane change control; and-   a termination announcement process of announcing termination of the    autonomous driving control when the steering intervention in said    same direction is performed, and establishment of the stop condition    is recognized, during execution of the autonomous lane change    control.

A second aspect of an embodiment of the present disclosure is thecontrol device for vehicle traveling according to the first aspectdiscussed above, further executing a process for determining whetherthere arises an excessive approach to an obstacle that is present on alane to which the vehicle intends to move based on a relative distancefrom the obstacle, during execution of the autonomous lane changecontrol, and

-   recognizing that said stop condition is established when the    presence of the excessive approach is affirmed.

A third aspect of an embodiment of the present disclosure is the controldevice for vehicle traveling according to the first aspect discussedabove, further executing a process for acquiring prohibition informationon lane change based on information that is read from an on-vehiclestorage device or information that is provided from outside of thevehicle, and

-   recognizing that stop condition is established when the vehicle is    recognized as located in a lane change prohibited area, based on the    prohibition information.

A fourth aspect of an embodiment of the present disclosure is thecontrol device for vehicle traveling according to the first aspectdiscussed above

-   wherein the autonomous lane change control is continued until    completion of lane change is determined, and-   the termination announcement process is executed when establishment    of the stop condition is recognized before end of the autonomous    lane change control, after occurrence of the steering intervention    in the same direction.

A fifth aspect of an embodiment of the present disclosure is the controldevice for vehicle traveling according to the first aspect discussedabove, further executing returning-to-original-lane control thatterminates the autonomous lane change control and causes the vehicle toreturn to an original lane autonomously, when establishment of the stopcondition is recognized before a steering intervention by the driveroccurs, after start of the autonomous lane change control, and

-   executing said termination announcement process when the steering    intervention in said same direction is performed by the driver    during execution of the returning-to-original-lane control.

A sixth aspect of an embodiment of the present disclosure is the controldevice for vehicle traveling according to the fifth aspect discussedabove, further executing returning-to-original-lane control thatterminates the autonomous lane change control and causes the vehicle toreturn to an original lane autonomously, when the driver performs asteering intervention in a counter direction to a direction of steeringthat is requested by the autonomous lane change control beforeestablishment of the stop condition is recognized, after start of theautonomous lane change control, and

-   executing a process of continuing the autonomous driving control    when the driver does not perform the steering intervention in said    same direction, during execution of the returning-to-original-lane    control.

A seventh aspect of an embodiment of the present disclosure is thecontrol device for vehicle traveling according to the first aspectdiscussed above, further executing returning-to-original-lane controlthat terminates the autonomous lane change control and causes thevehicle to return to an original lane autonomously, when the driverperforms a steering intervention in a counter direction to a directionof steering that is requested by the autonomous lane change controlbefore establishment of the stop condition is recognized, after start ofthe autonomous lane change control, and

-   executing the termination announcement process when the driver    performs the steering intervention in said same direction, during    execution of the returning-to-original-lane control.

An eighth aspect of an embodiment of the present disclosure is thecontrol device for vehicle traveling according to the first aspectdiscussed above, further executing a process of terminating theautonomous driving control, simultaneously with the terminationannouncement process, or subsequently to the termination announcementprocess.

Advantages of Embodiments of the Present Disclosure

According to the first aspect of the embodiment, when steering isperformed by the driver after autonomous lane change control is startedin response to receiving the instruction to start autonomous lanechange, the steering is given priority over autonomous lane changecontrol. Consequently, even after start of the autonomous lane change,the driver can take back vehicle control authority immediately.According to this rule, even under a situation in which the stopcondition of autonomous lane change is established, lane change isforced to be performed by the steering intervention in the samedirection as the autonomous lane change. According to the present aspectof the embodiment, in such a case, termination of the autonomous drivingcontrol is announced, whereby it can be made obvious that the intentionof the driver is different from the intention of the autonomous drivingcontrol. On the other hand, under a situation in which the stopcondition of autonomous lane change is not established, the steeringintervention in the same direction does not mean forceful lane change.If the driver were announced of termination of the autonomous driving inthis case, the driver might feel it troublesome. According to thepresent aspect of the embodiment, autonomous driving control iscontinued in such a case, so that the driver is never caused to beannoyed of this kind.

According to the second aspect of the embodiment, it can be determinedthat the stop condition of autonomous lane change is established, whenthe vehicle excessively approaches an obstacle on the lane to which thevehicle intends to move during execution of the autonomous lane changecontrol. Consequently, according to the present aspect of theembodiment, when the driver forces lane change under the situation inwhich such an excessive approach occurs, termination of the autonomousdriving control can be announced appropriately.

According to the third aspect of the embodiment, when the driver forceslane change in the lane change prohibited area, termination of theautonomous driving control can be announced appropriately.

According to the fourth aspect of the embodiment, when the stopcondition is established by a steering intervention by the driver afterstart of the autonomous lane change control, termination of theautonomous driving control can be appropriately announced.

According to the fifth aspect of the embodiment, when establishment ofthe stop condition is recognized under the situation in which the driverdoes not perform a steering intervention after the start of autonomouslane change control, the autonomous lane change control is terminated atthat point of time, and returning-to-original-lane control is started.When the driver wants to perform lane change, a steering intervention toa side to change the lane occurs at a stage when the vehicle shows abehavior of returning to the original lane. According to the presentaspect of the embodiment, when such steering intervention is performed,termination of the autonomous driving control can be announcedappropriately.

According to the sixth aspect of the embodiment, when steeringintervention in the direction to return the vehicle to the original laneis performed after the start of autonomous lane change control,returning-to-original-lane control is started, assuming that the driverrequests to stop lane change. When return to the original lane iscompleted without the driver changing his or her mind, it can bedetermined that the driver does not intend to force lane change.According to the present aspect of the embodiment, in such a case,autonomous driving can be continued as it is, and the driver can beprevented from being annoyed.

According to the seventh aspect of the embodiment, when a steeringintervention in the direction to return the vehicle to the original laneis performed after the start of autonomous lane change control,retuning-to-original-lane control is started, assuming that the driverrequests to stop lane change. When a steering intervention in thedirection of lane change is performed again, during execution of thereturning-to-original-lane control, it is determined that the intentionof the driver and the intention of the autonomous driving do notcoincide with each other, and termination of the autonomous driving canbe announced.

According to the eighth aspect of the embodiment, autonomous drivingcontrol can be terminated under the situation in which it is determinedthat the intention of the driver deviates from the intention of theautonomous driving control.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram for explaining the configuration of a firstembodiment of the present disclosure;

FIG. 2A illustrates a vehicle behavior in a case where the LC startinstruction is issued under a situation in which no obstacle such as anearby other vehicle is present;

FIG. 2B illustrates a vehicle behavior in a case where at the time pointof start of the autonomous LC control, a nearby other vehicle thattravels side by side with the vehicle is present on the passing lane;

FIG. 2C illustrates a vehicle behavior in a case where at the time pointof start of the autonomous LC control, a nearby other vehicleapproaching at a high speed is present behind the vehicle on the passinglane;

FIG. 2D illustrates a vehicle behavior in a case where a steeringintervention by the driver occurs under the situation illustrated inFIG. 2A;

FIG. 2E illustrates a state where lane change is forcibly done by thedriver under the situation illustrated in FIG. 2B;

FIG. 2F illustrates a state where lane change is forcibly done by thedriver after returning-to-original-lane control is started under thesituation illustrated in FIG. 2C;

FIG. 3 illustrates a state transition diagram concerning the vehicle thepresent embodiment; and

FIG. 4 is a flowchart of a routine executed by the ECU in the presentembodiment.

DETAILED DESCRIPTION First Embodiment [Hardware Configuration of FirstEmbodiment]

FIG. 1 illustrates a hardware configuration of an autonomous drivingvehicle 10 equipped with a control device for vehicle travelingaccording to a first embodiment of the present disclosure. Asillustrated in FIG. 1, the vehicle 10 is equipped with a stereo camera12. The stereo camera 12 can pick up a stereoscopic image of a front ofthe vehicle 10 at a predetermined viewing angle. It is also possible toreplace the stereo camera 12 with a monocular camera.

Further, a plurality of LIDAR (Laser Imaging Detection and Ranging)units 14 are mounted on the vehicle 10 in such a manner as to surroundthe vehicle. More specifically, six of the LIDAR units 14 in total aremounted so that a region in front of the vehicle, left and right regionsin front of the vehicle, a region behind the vehicle, left and rightregions behind the vehicle are detection regions. According to the LIDARunits 14, outlines of objects present in the respective detectionregions and distances to the objects can be detected.

Furthermore, a plurality of millimeter wave radar units 16 are mountedon the vehicle 10 so as to surround the vehicle. Five of the millimeterwave radar units 16 in total are mounted so that the region in front ofthe vehicle, the left and right regions in front of the vehicle, and theleft and right regions behind the vehicle are detection ranges.According to the millimeter wave radar units 16, distances to objectspresent in the respective detection regions, and relative speeds of theobjects and the vehicle 10 can be detected.

Hereunder, the stereo camera 12, the LIDAR units 14 and the millimeterwave radar units 16 described above are collectively referred to as“object recognition sensors”.

The vehicle 10 is equipped with an ECU (Electronic Control Unit) 18.Detection signals of the aforementioned “object recognition sensors” aresupplied to the ECU 18. Based on the detection signals, the ECU 18 candetect nearby other vehicles, pot holes on road, pylons placed in aconstruction site and the like, a fallen object left on a road, a tailend of congestion and the like. Hereunder, these matters will becollectively referred to an “obstacle”.

The vehicle 10 is also equipped with a GPS (Global Positioning System)unit 20. According to the GPS unit 20, a present location of the vehicle10 can be detected by using a GPS. An output signal of the GPS unit 20is supplied to the ECU 18. Map data is stored in the ECU 18. The ECU 18can determine a present location of the vehicle 10 on a map, and furthercan determine whether or not the present location of the vehicle 10belongs to a lane change prohibited area, based on the map data and thesignals sent from the GPS unit 20.

In the present embodiment, the ECU 18 can execute autonomous operationcontrol for causing the vehicle 10 to travel autonomously. Theautonomous driving control includes autonomous lane change control(hereunder, referred to as “autonomous LC control”) for causing thevehicle 10 to perform lane change autonomously.

Autonomous LC control is started by any one of the following threecases.

(1) In a case where the ECU 18 determines start of lane change

(2) In a case where the driver instructs start of autonomous LC control

(3) In a case where the ECU 18 proposes implementation of lane change tothe driver, and the driver approves implementation of lane change

In the present embodiment, in an interior of the vehicle 10, aninterface (a switch or the like) for the driver to input an instructionor approval concerning autonomous driving, and an interface (a lamp, aspeaker or the like) for the ECU 18 to propose implementation of lanechange to the driver are disposed (none of them is illustrated). In anycase, when autonomous LC control is started, flashing of a directionindicator is started, and notification of start of the autonomous lanechange is issued. The start of flashing and issuing of notification maybe simultaneously performed, or either one of them may be performedfirst.

Hereunder, in the case of (1) described above, determination of start oflane change by the ECU 18 corresponds a “start instruction” ofautonomous lane change. Further, in the case of (2) or (3) describedabove, the instruction or the approval by the driver corresponds thestart instruction of autonomous lane change. Further, in any case, atime point at which flashing of the direction indicator or notificationof autonomous driving is started subsequently to the start instructionthereof can be regarded as the same as a time point of the “start ofautonomous LC control”.

[Feature of First Embodiment]

FIGS. 2A to 2F are views for explaining behaviors that can occur in thevehicle 10 after the start of autonomous LC control. In a road in eachof the drawings, a left side of a broken line 22 is set as a travellane, and a right side of the broken line 22 is set as a passing lane.During execution of autonomous driving control, the ECU 18 may determinewhether or not to try to pass, based on a relative distance to apreceding vehicle 24 based on a relative speed and the relativedistance. When determining to do passing, the ECU 18 issues aninstruction to start autonomous lane change (hereunder, referred to asan “LC start instruction”) at a time point of the decision making.

FIG. 2A illustrates a behavior in a case where the LC start instructionis issued under a situation in which no obstacle such as a nearby othervehicle is present. In this case, the vehicle 10 can quickly start lanechange after startup of the autonomous LC control, and will be able tosmoothly complete lane change.

FIG. 2B illustrates an example of a behavior in a case in which at thetime point of start of the autonomous LC control, the nearby othervehicle 26 that travels side by side with the vehicle 10 is present onthe passing lane. According to the autonomous LC control, in such acase, an instruction to wait for a chance of lane change until thenearby other vehicle 26 overtakes the vehicle 10 and runs ahead isissued. Subsequently, lane change is performed after the nearby othervehicle 26 runs ahead.

FIG. 2C illustrates an example of a behavior in a case in which at thetime point of start of the autonomous LC control, the nearby othervehicle 26 approaching at a high speed is present behind the vehicle 10,on the passing lane. Under such a situation, after lane change isstarted by the autonomous LC control, presence of the nearby othervehicle 26 may be detected in the vehicle 10 during the lane change. Inthis case, the autonomous driving control of the present embodimentstops the autonomous LC control, and executes“returning-to-original-lane control”. The returning-to-original-lanecontrol is designed so as to return the vehicle 10 which is in thecourse of lane change to the original travel lane. As a result, in thevehicle 10, a returning behavior as illustrated in FIG. 2C appears.

in the present embodiment, when there arises an intervention of adriving operation by the driver during execution of autonomous drivingcontrol, the ECU 18 gives priority to the operation by the driver overthe operation requested by the autonomous driving control. For example,when the driver starts a steering operation, after flush of thedirection indicator is started or announcement of the autonomous lanechange start is provided following the start of the autonomous LCcontrol and before vehicle behavior due to the autonomous LC controlappears, the ECU 18 gives a steering angle corresponding to the steeringoperation to the wheels to be steered.

FIG. 2D illustrates a behavior in a case in which a steeringintervention by the driver occurs under the situation illustrated inFIG. 2A. In FIG. 2D, as a result of the steering intervention, lanechange is completed earlier as compared with the case of FIG. 2A. Whenthere is an intervention by the driver during execution of autonomousdriving, it is conceivable to cancel the autonomous driving immediately,and return the driving authority to the driver. However, under thesituation in which no other vehicle exists around the vehicle 10, therearises no practical inconvenience by the assist in lane change by thedriver. Further, in this case, the intention of the driver and theintention of the autonomous LC control coincide with each other in thepoint of carrying out lane change. When autonomous driving is canceledunder such a situation, the driver has to set the autonomous drivingagain, and being apt to feel annoyance. Consequently, the presentembodiment does not cancel the autonomous driving by the steeringintervention by the driver, and continuously executes the autonomousdriving control also after disappearance of the intervention in such acase.

FIG. 2E illustrates a state in which the driver forces to lane changeunder the situation illustrated in FIG. 2B. FIG. 2F illustrates a statein which the driver forces lane change after thereturning-to-original-lane control is started under the situationillustrated in FIG. 2C. That is, FIG. 2D and FIG. 2F both illustrate thestates in each of which the driver forces lane change in such a manneras to cut in before the nearby other vehicle 26 under the situation inwhich a stop condition of autonomous lane change (hereunder, referred toas “an LC stop condition”) is established. Such forceful lane changecould force the nearby other vehicle 26 to take sudden braking.Moreover, in regard with implementation of lane change, the intention ofthe driver is totally different from the intention of autonomous LCcontrol. Such a situation tends to occur when the driver is in a moreurgent state with respect to a move plan on which autonomous driving isbased. If the autonomous driving is continued under such a situation,the driver is apt to feel a sense of discomfort. Thus, in the case inwhich lane change is forced by the driver under the situation in whichthe LC stop condition is established, the present embodiment cancels theautonomous driving quickly after providing an announcement for noticingit.

[Operation of First Embodiment]

FIG. 3 is a state transition diagram concerning the vehicle 10 of thepresent embodiment. Hereunder, with a state 100 of “autonomous drivingOFF” as a starting point, various states and state transitions occurringin the vehicle 10 will be described.

When the driver inputs a system start instruction in the state 100 ofautonomous driving OFF, the vehicle 10 transitions to a state 102 oflane keeping control. On the other hand, when in the state 102 of lanekeeping control, a system end instruction is inputted, the state 102transitions to the state 100 of autonomous driving OFF.

In the state 102 of lane keeping control, processing is performed, whichis for causing the vehicle 10 to travel along the same lane with aguardrail and a white line on the lane as marks. For example, when thetravel speed is specified, lane keeping control in which the vehiclespeed is kept to the specified one is performed. Further, when afollowing distance from a preceding vehicle is specified, lane keepingcontrol in which the distance is kept to the specified one is performed.

When the LC start instruction occurs in the state 102 of lane keepingcontrol, the vehicle 10 transitions to a state 104 of autonomous LCcontrol. The transition occurs specifically when the ECU 18 itselfdetermines start of lane change, when the driver instructs start ofautonomous lane change, or when the driver approves autonomous lanechange that is proposed by the ECU 18.

In the state 104 of autonomous LC control, processing for moving thevehicle 10 to a target lane is performed. In the state 104, it isfirstly determined whether the lane to which the vehicle intends to moveis located on either a left of the vehicle 10, or a right of the vehicle10. Next, flashing of the direction indicator is started. Subsequently,start of the autonomous lane change is announced to the driver.Thereafter, whether or not lane change is possible is determined inaccordance with the situation of the nearby other vehicles and the like.That is, it is determined whether a condition under which the lanechange should be stopped has been established.

In this stage, following determinations are performed specifically.

(1) Whether an obstacle that hinders travel of the vehicle 10 is presenton the lane to which the vehicle intends to move?

(2) Whether the present location of the vehicle 10 belongs to a lanechange prohibited area?

It will be determined that an obstacle is present, when a nearby othervehicle that is predicted to approach the vehicle 10 excessively ispresent in the lane to which the vehicle intends to move based on arelative distance, or based on a relative speed and the relativedistance, for example. Further, when a pot hole on road, pylons in aconstruction site and the like are present in positions that hindertravel of the vehicle 10, presence of obstacles is also determined.

When it is determined that the LC stop condition is established as aresult of the above described processing, lane change is not starteduntil the condition is cancelled. When it is determined that lane changeis possible, processing of acceleration or deceleration and steering formoving the vehicle 10 to the target lane is started. The processing fordetermining the LC stop condition, and the processing of acceleration ordeceleration and steering are repeatedly carried out until lane changeis completed. When completion of move to the adjacent lane isdetermined, the autonomous LC control is terminated, and transition tothe state 102 of lane keeping control occurs.

In the present embodiment, the ECU 18 determines that a steeringintervention by the driver occurs, when detecting a steering amount (ora steering force) exceeding a threshold value. When a steeringintervention in the same direction as autonomous lane change occursduring execution of autonomous LC control, the state of the vehicle 10transitions to a state 106 of driver's steering preference. In the state106, an arithmetic operation concerning the autonomous LC control iscontinued, but a steering amount by the driver has priority over asteering amount by the arithmetic operation.

As described above, after start of the autonomous LC control, it isrepeatedly determined whether or not the LC stop condition isestablished, until lane change is completed. In the state 106 ofdriver's steering preference, steering of the driver has priorityirrespective of whether or not the LC stop condition is established.

The driver may perform steering operation for the purpose of promotingchange in behavior by autonomous LC control after confirming that thereis no matter that hinders lane change. In such a case, the LC stopcondition is not established during the steering intervention by thedriver. In other words, if the LC stop condition is not establishedduring the steering intervention, it can be determined that the driverdoes not intend to force lane change against the determination of theautonomous LC control. In this case, the ECU 18 transfers the state 106of driver's steering preference to the state 104 of autonomous LCcontrol after termination of the steering intervention by the driver.

When establishment of the LC stop condition is recognized in the state106 of driver's steering preference, it can be determined that thedriver intends to force lane change against the determination of theautonomous LC control. In this case, the ECU 18 transfers the state 106of driver's steering preference to a state 108 of announcement oftermination of autonomous driving, after the steering intervention isterminated. The transition may be caused at a time point at whichestablishment of the LC stop condition is determined, or at a time pointat which completion of lane change is determined.

In the state 108 of announcement of termination of autonomous driving,the driver is notified of stop of the autonomous driving. Thereafter,the autonomous driving is cancelled when a predetermined time periodelapses. As a result, the state of the vehicle 10 transfers to the state100 of autonomous driving OFF, and the driving operation authority istaken over by the driver (i.e., takeover of the authority by the driveroccurs). When the driver desires restart of autonomous driving, thedriver needs to input the system start instruction again. It should benoted that transition may be made to the state 102 of lane keepingcontrol from the state 108 without cancelling the autonomous drivingwhen the driver issues a continuation instruction quickly after thetermination of the autonomous driving is announced.

In some cases, the autonomous LC control may be started under asituation in which the driver does not desire lane change. In that case,the driver may perform steering operation in a counter direction fromthe lane change (hereunder, this operation is referred to as “counterdirection steering”) at a stage at which a behavior of autonomous lanechange appears in the vehicle 10. Such steering intervention may alsooccur when the driver recognizes presence of an obstacle before the ECU18.

When an intervention of the counter direction steering occurs in thestate 104 of autonomous LC control the ECU 18 transfers the state 104 toa state 110 of driver's steering preference. In the state 110, all ofthe processing of the autonomous LC control are stopped, and thereafter,steering by the driver is reflected in the behavior of the vehicle 10.

When the intervention of the counter direction steering is terminated inthe state 110 of driver's steering preference, the ECU 18 transfers thestate 110 to a state 112 of retuning-to-original-lane control. In thereturning-to-original-lane control, processing of acceleration ordeceleration and steering for returning the vehicle 10 to the originallane is executed. When completion of return to the original lane isdetermined, the state of the vehicle 10 is transferred to the state 102of lane keeping control.

In the state 104 of autonomous LC control, establishment of the LC stopcondition may be determined after autonomous steering is started. Inthis case, the ECU 18 stops the autonomous LC control to transfer thestate of the vehicle 10 to the state 112 of returning-to-original-lanecontrol. As a result, the returning-to-original-lane control is started,and the vehicle 10 that had once started to move to the adjacent lanestarts to return to the original lane. Thereafter, when completion ofreturn to the original lane is determined, the state of the vehicle 10is transferred to the state 102 of lane keeping control.

A steering intervention of the driver may occur in the state 112 ofreturning-to-original-lane control. Specifically, (1) after theautonomous LC control recognizes establishment of the LC stop conditionand the state of the vehicle 10 is transferred to the state 112 ofreturning-to-original-lane control, the driver may perform steeringoperation to force lane change. In that case, it can be determined thatthe intention of the driver does not coincide with the determination ofthe autonomous driving.

A similar steering intervention also occurs (2) when the driver who hassteered in the counter direction to stop lane change temporarily afterstart of the autonomous LC control turns the steering direction towardthe lane change side while changing his or her mind. In that case, itcan be read that the driver does not accept the determination of theautonomous driving. That is, in each of the cases of (1) and (2)described above, it can be determined that the intention of the driverdoes not coincide with the determination of autonomous drivingconcerning whether or not to perform lane change. Consequently, when asteering intervention to the direction of lane change occurs in thestate 112 of returning-to-original-lane control, the ECU 18 givespriority to the steering intervention, and thereafter transfers thestate of the vehicle 10 to the state 108 of announcement of thetermination of the autonomous driving. After the transition occurs, thedriver is notified of the termination of the autonomous driving, andthereafter, the autonomous driving is canceled (similar to the case ofthe transition from the state 106 to the state 108).

In the state 112 of returning-to-original-lane control, a steeringintervention to a direction to assist return to the original lane mayoccur. In that case, since the intention of the driver concerning lanechange coincides with the determination of autonomous driving, thesteering of the driver is given priority while an arithmetic operationconcerning the returning-to-original-lane control is continued.Subsequently, at a time point at which the steering intervention ends,the returning-to-original-lane control is restarted.

[Process Flow in First Embodiment]

FIG. 4 is a flowchart of a routine executed by the ECU 18 in the presentembodiment. The routine illustrated in FIG. 4 is started up by thedriver inputting a start instruction of autonomous driving control, thatis, a system start instruction. When the routine is started up, lanekeeping control is firstly executed (step 120). The lane keeping controlis achieved by a plurality of processes being sequentially executed. Inthe present step, one step of these processes is executed in order inevery one cycle.

When the above described processing is completed, it is determinedwhether or not an operation for terminating the autonomous drivingcontrol is performed (step 122). That is, it is determined whether ornot a system termination instruction is inputted by the driver.

When it is determined that the above operation is performed, theautonomous driving control is terminated. When the above operation isnot detected, it is determined whether or not an LC start instruction isgenerated (step 124).

When generation of an LC start instruction is not recognized, theprocessing in step 120 described above is executed again. Thereby, theprocessing of lane keeping control proceeds by one step. Hereafter, theabove described processes are repeated until an operation fortermination of the autonomous driving control or an LC start instructionis generated.

When generation of an LC start instruction is recognized in step 124, itis subsequently determined whether or not a steering intervention by thedriver occurs (step 126). Specifically, it is determined whether or nota steering amount or a steering force that exceeds a threshold value isinputted by the driver.

When it is determined that a steering intervention does not occur,autonomous LC control is executed (step 128). The autonomous LC controlis achieved by a plurality of processes being sequentially executed. Inthe present step, one step of the processes is executed in every onecycle.

When the above described processing is completed, it is subsequentlydetermined whether or not the LC stop condition is established (step130). That is, it is determined whether an obstacle that hinders lanechange of the vehicle 10 is present, and whether a present location ofthe vehicle 10 is within a lane change prohibited area.

When establishment of the LC stop condition is not recognized, it isdetermined whether or not lane change is completed (step 132). Here,completion of lane change is determined when a center position of thevehicle 10 reaches a center of the lane to which the vehicle intends tomove, for example.

When it is determined that lane change is not completed yet, theprocessing in step 126 described above is executed again. If a steeringintervention by the drive does not occur, processes of lane keepingcontrol proceed by one step in step 128. Thereafter, processes in steps126 to 132 are repeated until occurrence of a steering intervention orestablishment of the LC stop condition is recognized. When completion ofthe lane change is recognized in step 132, the processes in step 120described and the following steps are started again.

When the LC stop condition in step 130 is established in the course ofthe above described processes being repeated, returning-to-original-lanecontrol is executed to stop lane change and return the vehicle 10 to theoriginal lane (step 134). The returning-to-original-lane control isachieved by a plurality of processes being sequentially executed. In thepresent step, one step of the processes is executed in every cycle.

When the processing described above is completed, it is determinedwhether or not a steering intervention to the direction of lane changeoccurs (step 136). That is, it is determined whether or not steering inthe direction to force lane change is performed by the driver.

When such steering intervention is not recognized, it is determinedwhether or not return to the original lane is completed (step 138). Thecompletion can be determined at a time point at which the centerposition of the vehicle 10 reaches a center of the original lane, forexample.

When completion of return to the original lane is not recognized, theprocessing in step 134 described above is executed again. This causesthe processes of retuning-to-original-lane control to proceed by onestep. Thereafter, if a steering intervention to force lane change doesnot occur, the processes in steps 134 to 138 are repeated. Whencompletion of return to the original lane is recognized in step 138, theprocesses of step 120 described above and the following steps arestarted again.

When the driver provide a steering intervention in the direction toforce lane change in the course of the processes in steps 134 to 138being repeated, that is, in the course of the retuning-to-original-lanecontrol being repeatedly executed, establishment of the condition isdetermined in step 136. In this case, termination of the autonomousdriving control is announced first (step 140), and subsequently, theautonomous driving control is terminated.

When a steering intervention by the driver occurs in the course of theprocesses in step 120 and the following steps being repeated, thecondition in step 126 is established. In this case, it is subsequentlydetermined whether or not the direction of the intervention coincideswith the direction of lane change (step 142).

When the direction of the steering intervention differs from thedirection of lane change, it can be determined that the driver intendsto stop lane change and return the vehicle 10 to the original lane. Inthat case, the processes in step 134 and the following steps areexecuted thereafter.

When the direction of the steering intervention coincides with thedirection of lane change, it is determined whether or not the LC stepcondition is established, subsequently from step 142 (step 144).

If the LC stop condition is not established at this time point, it canbe determined that the steering intervention of the driver does notintend to force lane change, but intends to promote lane change. In thiscase, steering control by autonomous LC control is temporarily stoppedwhile the arithmetic operation concerning the autonomous LC control iscontinued (step 146). Thereafter, the processes in steps 126 to 142 to144 to 146 are repeatedly executed. As a result, the state of driver'ssteering preference is implemented while the arithmetic operation ofautonomous LC control is continued. When the steering intervention bythe driver disappears, the determination in step 126 becomes not beingestablished, and autonomous LC control is restarted.

On the other hand, when the LC stop condition in step 144 is establishedin the course of the processes in step 126 to 142 to 144 to 146 beingrepeated, it can be understood that the driver forces lane changeagainst the determination of the autonomous driving control. In thiscase, thereafter, the autonomous driving control will be terminatedafter the processing of step 140.

In the above described explanation, the autonomous driving control isinevitably terminated after the announcement of the termination of theautonomous driving control in step 140. However, the flow of the processis not limited to this. That is, a step of confirming the intention ofthe driver may be interposed after step 140, and when the intention ofcontinuation of autonomous driving is detected, the processes in step120 and the following steps may be executed after completion of lanechange.

As described above, according to the routine illustrated in FIG. 4, thestate transition described with reference to FIG. 3 can be achieved inthe vehicle 10. According to the state transition illustrated in FIG. 3,if the driver provide a steering intervention during execution ofautonomous LC control, the steering authority can be given to thedriver. And, the driver is not caused to be annoyed, because theautonomous driving control is not canceled when the steering is topromote lane change. Further, when the steering is to force lane change,termination of the autonomous driving control is announced, and further,the autonomous driving control is terminated, whereby the driver canavoid feeling a sense of discomfort to autonomous driving.

What is claimed is:
 1. A control device for vehicle traveling thatexecutes autonomous driving control that causes a vehicle to travelautonomously, the autonomous driving control including autonomous lanechange control that achieves autonomous lane change of a vehicle, andthe control device for vehicle traveling executing: a process ofstarting the autonomous lane change control in response to receiving aninstruction to start the autonomous lane change; a process ofdetermining whether or not a stop condition of the autonomous lanechange is established; a process of giving priority to steering of adriver over steering that is caused by the autonomous lane changecontrol when there is a steering intervention by the driver duringexecution of the autonomous lane change control; a process of continuingthe autonomous driving control when a driver performs a steeringintervention in a same direction as a direction of steering that isrequested by the autonomous lane change control, and establishment ofthe stop condition is not recognized, during execution of the autonomouslane change control; and a termination announcement process ofannouncing termination of the autonomous driving control when thesteering intervention in said same direction is performed, andestablishment of the stop condition is recognized, during execution ofthe autonomous lane change control.
 2. The control device for vehicletraveling according to claim 1, further executing a process fordetermining whether there arises an excessive approach to an obstaclethat is present on a lane to which the vehicle intends to move based ona relative distance from the obstacle, during execution of theautonomous lane change control, and recognizing that said stop conditionis established when the presence of the excessive approach is affirmed.3. The control device for vehicle traveling according to claim 1,further executing a process for acquiring prohibition information onlane change based on information that is read from an on-vehicle storagedevice or information that is provided from outside of the vehicle, andrecognizing that stop condition is established when the vehicle isrecognized as located in a lane change prohibited area, based on theprohibition information.
 4. The control device for vehicle travelingaccording to claim 1, wherein the autonomous lane change control iscontinued until completion of lane change is determined, and thetermination announcement process is executed when establishment of thestop condition is recognized before end of the autonomous lane changecontrol, after occurrence of the steering intervention in the samedirection.
 5. The control device for vehicle traveling according toclaim 1, further executing returning-to-original-lane control thatterminates the autonomous lane change control and causes the vehicle toreturn to an original lane autonomously, when establishment of the stopcondition is recognized before a steering intervention by the driveroccurs, after start of the autonomous lane change control, and executingsaid termination announcement process when the steering intervention insaid same direction is performed by the driver during execution of thereturning-to-original-lane control.
 6. The control device for vehicletraveling according to claim 1, further executingreturning-to-original-lane control that terminates the autonomous lanechange control and causes the vehicle to return to an original laneautonomously, when the driver performs a steering intervention in acounter direction to a direction of steering that is requested by theautonomous lane change control before establishment of the stopcondition is recognized, after start of the autonomous lane changecontrol, and executing a process of continuing the autonomous drivingcontrol when the driver does not perform the steering intervention insaid same direction, during execution of the retuning-to-original-lanecontrol.
 7. The control device for vehicle traveling according to claim1, further executing retuning-to-original-lane control that terminatesthe autonomous lane change control and causes the vehicle to return toan original lane autonomously, when the driver performs a steeringintervention in a counter direction to a direction of steering that isrequested by the autonomous lane change control before establishment ofthe stop condition is recognized, after start of the autonomous lanechange control, and executing the termination announcement process whenthe driver performs the steering intervention in said same direction,during execution of the returning-to-original-lane control.
 8. Thecontrol device for vehicle traveling according to claim 1, furtherexecuting a process of terminating the autonomous driving control,simultaneously with the termination announcement process, orsubsequently to the termination announcement process.